A Study of Radiation Fog Formation Frequency and Duration in the Benue River Valley

Radiation fog is a meteorological phenomenon of considerable practical significance across Nigeria's river valleys, where clear skies, moist soils, and gentle winds create conditions favorable for fog development during the transition seasons. This study examines the frequency, duration, and seasonal distribution of radiation fog events in the Benue River Valley, focusing on the Makurdi area in Benue State. Hourly visibility and weather observations from the NiMet Makurdi Airport station spanning 2017 to 2023 were analyzed to identify and classify fog events by onset time, dissipation time, and minimum visibility reached. Supplementary meteorological variables including minimum temperature, dew point depression, wind speed, and cloud cover were examined as fog-favoring conditions using logistic regression. Results show that radiation fog occurs on an average of 31 nights per year in Makurdi, with 85 percent of events confined to the October-to-January transition period immediately following the retreat of the rainy season. Minimum visibility during fog episodes averages 180 metres, with occasional dense fog below 50 metres recorded in November. The logistic regression model identifies minimum temperature below 19 degrees Celsius, wind speed below 2 metres per second, and cloud cover below 2 oktas as the strongest combination of fog-favoring predictors. Practical implications for road transport and aviation operations in the Benue Valley are discussed, with recommendations for community road safety advisories. Keywords: radiation fog, Benue River Valley, visibility, fog formation, road safety.